Biometrics gain increasing interest as a solution to many security issues. In biometrics, a human being is identified by measuring one or more biometric features of the body. Biometric data are said to identify a person based on “who he is”, rather than on “what he has” (such as a smartcard) or “what he knows” (such as a password).
Using a biometric system a prover may identify or authenticate himself to a verifier. When a biometric system is used to find or check the identity of a person, there are two options: In identification the identity of the prover is not a priori known, but based on the measured biometric feature, a search is performed in a database to find a match; In verification, the prover not only allows a measurement of his or her biometric feature but also claims what his or her identity is. Biometric features include fingerprint, iris, retina, palm etc.
An unresolved issue, however, is that when deployed at large scale, a citizen looses privacy as he must reveal his identifying biometric data to his bank, to the government, etc. Each of them will obtain the same measured data, and unless special precautions are taken there is no guarantee that none of these parties will ever misuse the biometric data to impersonate the citizen.
In the article “New Shielding Functions to Enhance Privacy and Prevent Misuse of Biometric Templates” of Jean-Paul Linnartz and Pim Tuyls, introduces helper data generating functions to improve on this aspect; the article is further referred to as ‘Linnartz’. During an enrollment phase, a prover Peggy receives a biometric template comprising biometric helper data and verification data.
During a usage phase, Peggy allows Victor to take a, possibly noisy, measurement Y=X+N of her biometric feature X; N represents noise. Victor maps the obtained biometric data to reproducible biometric data under control of the biometric helper data so as to reduce the noise from the obtained biometric data. Victor then applies a cryptographic hash function to the reproducible biometric data to obtain an output U, which is compared to a reference authentication response. Here, X, N, and Y are real, or complex, valued vectors.
US patent application US2006/0274920 from O. Tochikubo et al. describes a personal identification device comprising a finger print sensor and, to allow verification, a scanner that receives fingerprint comparison data from a storage medium mounted on a portable device worn on a finger, a wrist, or an ankle of a user. International patent application WO2010/064162A1 by S. Corroy et al. describes a secure identification system in which a user gets access through an identification device or badge or tag worn on his/her body, which applies the techniques of body coupled communication (BCC) to create a kind of aura around the user. An identification (ID) is communicated to a user interface of the secure identification system through BCC communication, and the user is authenticated by the system through an authentication procedure checking the identity of the user on the basis of an assumed secure BCC communication of the ID.